Apply the size title to the entire cell

When a change is very small (e.g.  5 lines) the size bar is so few
pixels it is nearly impossible to hover over it and see the tooltip.
Apply the title to the entire table cell, giving the user a much
larger target to hover on.

Change-Id: I6ce8ab3a2e55279a9d6345aced42f8c179c608cf